FFMPEG issue with the examples

[balloch]

Minor issue, but worth mentioning: this library has no explicit requirements for FFMPEG, but recordings of the videos seem to depend pretty heavily on the -crf command (example: cell:4;line:6 in the CartPole example). It seems to presume a recent FFMPEG build and "It assumes you have ffmpeg compiled with --enable-libx264" (from here ). I tried to tinker with it and get it to work with the encoders listed in ffmpeg -codecs | grep 264, by I had no luck (I'm not a heavy user of ffmpeg). Do you have a suggestion for getting around this without recompiling ffmpeg (aka using the precompiled ffmpeg from apt, or the precompiled version included with conda/pip python libraries ?